The goal of this Program is to develop a mechanistic understanding of the link between lipid oxidation and vascular pathology. The senior research team is a highly interactive multidisciplinary group with a broad range of shared expertise, including cell biology, chemical biology, biochemistry, and immunology. The 4 interrelated projects will test the hypothesis that oxidation of phospholipids in lipoproteins and cell membranes creates specific ligands for vascular cell receptors, transporters, and enzymes that then drastically alter cellular function and contribute to the pathogenesis of inflammatory diseases, including atherosclerosis. Project 1 will combine biophysical and clinical studies to define the chemical structures, biophysical properties, and oxidative pathways that participate in the formation, decay, and receptor binding activities of a novel family of specific oxidized phospholipid ligands of the Class B scavenger receptor CD36. This project will also assess the clinical relevance of specific oxidized phospholipids in human athero-sclerosis. Project 2 will determine how vascular cells clear biologically active and toxic components of oxLDL by defining the fate of extracellular oxidized phospholipids, characterizing transporters and transport mechanisms of oxidized phospholipids, and determining signaling pathways connecting oxLDL and phospholipids to cell viability. Project 3 will define complex mechanisms that regulate expression and activity of monocyte/macrophage 15- lipoxygenase, the enzyme responsible for producing 13-HPODE, an oxidation product of linoleic acid and a prominent oxidized lipid found in atheroma. Project 4 will define vascular cell signaling pathways initiated by binding of specific oxidized phospholipids to CD36, focusing on how this signaling cascade modulates foam cell formation, inflammatory responses, and metabolic pathways. An Administrative Core and 2 scientific cores, "Analytic and Synthetic Chemistry" and "Monocyte/Macrophage Cell Biology" strengthen the Program by providing well characterized, uniform-quality cellular, animal, and chemical reagents.